Secretion of all of the various salivary glands constitute the saliva found in the oral cavity. In normal health, saliva acts as a buffering fluid which aids in the regulation of the environment of the oral cavity. Yet, the cellular control mechanims involved in the secretory processes which regulate the production and composition of saliva are poorly understood. A better understanding of the secretory process will provide important information regarding the normal sequence of events that must occur if secretion is to take place and will also provide essential data that are required if we are to better understand the possible dysfunction of these glands in disease; such as, cystic fibrosis. Thus, we are proposing to study certain aspects of the stimulus-secretion coupling mechanism in rat submandibular tissue. In particular, we are proposing to study the possibility that certain cellular phosphorylation steps regulate the secretion of mucin from these cells and that the extent of phosphorylation of these endogenous proteins is regulated by the intracellular levels of cyclic AMP and calcium. Therefore, we intend to: (1) characterize the cyclic AMP-dependent protein kinase(s) present in the rat submandibular cells and then compare the extent of activation with the changes in the cellular levels of cyclic AMP (2) compare the extent of cAMP-PK activation with changes in endogenous protein phosphorylation/dephosphorylation to see if specific proteins are being phosphorylated/dephosphorylated during the secretory response. (3) use certain cyclic AMP analogs, cellular calcium depletion, and the calcium ionophore A-23187 to study the interrelationship between cyclic AMP metabolism and calcium metabolism in the secretion of mucins from these cells.